@Anthony I have looked at your log quadplane-2016-10-04.BIN
Some notable problems:
- it has TRIM_THROTTLE=100, which makes no sense. Can you really only achieve cruise speed at full throttle?
- at full throttle with the nose down the plane did not gain speed. That makes no sense. Is the fwd motor really working? Is it appropriately sized?
- you had THROTTLE_NUDGE=1 and had the throttle stick pushed to max. That means it was aiming for a airspeed of ARSPD_FBW_MAX which was 25. It clearly can’t achieve that. Are you aware of how THROTTLE_NUDGE works?